Brush and method of making same



March 23, 1954 R. o. PETERSON ET AL 2,672,640

BRUSH AND METHOD OF MAKING SAME Filed May 25, 1945 2 Sheets-Sheet 1 a c-W INVENTOR R BEN ETERSON BY FLETC C.MILES ATTORNEYS March 1954 R. o.PETERSON ET AL BRUSH AND METHOD OF MAKING SAME 2 Sheets-Sheet 2 FiledMay 23, 1945 INVENTORS RUBEN OPETERSON 0nd FLETCHER C. MILES rim MATTORNEYS Patented Mar. 23, 1954 BRUSH AND METHOD OF MAKING SAME Ruben0. Peterson,

Fletcher C. Miles,

University Heights, and

Cleveland, Ohio, assignors to The Osborn Manufacturing Company,Cleveland, Ohio, a corporation of Ohio Application May 23, 1945, SerialNo. 595,422

6 Claims. 1

The present improvements, relating to brush manufacture generally, havemore particular regard to the manufacture of closely packed brushes offine stranded or filamental material. However, as will appear, suchimprovements are not necessarily limited in their application to such orany particular type of brush, although the stranded material whereof thebrush is made will require to be selected with a view to its adapt--ability to the novel method of manufacture involved.

Heretofore in the manufacture of closely packed brushes of fine strandedor filamental material one or the other of two well known methods hasbeen employed. One such method involves folding over the brush material,the doubled strands then being held by some mechanical means such as astaple, retaining wire, or the like, with or without the assistance ofan auxiliary binder or adhesive. The other method involves the settingof the ends of such stranded or filamental brush material assembled intodesired form in a suitable binder such as an adhesive or cement whichwill harden upon drying or upon being subjected to other appropriatetreatment.

The use of the latter method has always involved certain unavoidabledifficulties. The binder employed must necessarily adhere to theindividual strands of the brush material and therefore wet them, at somestage of manufacture. However, particularly in the case of closelypacked stranded material such binder is drawn up between the strands bycapillarity so that if the binder is of such a nature that it willpenetrate closely packed brush material there is a tendency for it to bedrawn up far enough to render this method of manufacture unsatisfactory,particularly in the case of short-trimmed brushes, and in any event thebrush material will be set in or retained by the binder to an unevendegree so that uniformity of product is difficult to attain. Also, theproduction of short-trimmed brushes in the past has involved thehandling of short cuts of filamental material with attendantmanufacturing dimculties which are avoided by use of our new method.When the strands or bristles are too short to be combed into parallelalignment it has been necessary to carefully cut, sort,and stack suchshort bristles by hand prior to insertion in the brush back. By our newI method we are enabled to manufacture brushes with closely compactedbut very short bristles in a substantially continuous process.

Within recent years a number of synthetic plastics capable of beingdrawn in monofilament 2 form have been made available for use as brushmaterial. Such synthetic fiber forming products include polymeric amideshaving a protein-like chemical structure known under the trade namenylon, vinyl resin fibers, vinylidene chloride fibers and varioussynthetic rubber-like plastics. From the foregoing and other compoundsthus. available in stranded form for use as brush material, thosecharacterized as thermoplastic may be utilized in the present improvedmethod of brush manufacture. Such method is based on the discovery thatby simply applying heat in the proper manner to the base of an assemledgroup or bundle of strands of such thermoplastic syn- I theticfilamental material the corresponding ends of the component strands areinterfused and joined to form a secure bond for each such strand orfilament. At the same time a more or less flexible base to which suchstrands or filaments are permanently attached is provided. A furtherimportant result is that the interfusion of such ends can be controlledso that the base thus formed is of uniform thickness (or thinness)throughout, with no consequential variation in the degree to which thecomponent strands or filaments are bound together. In other words, theeffect is entirely different from that where a binder such as referredto above is employed in that there is no excessive capillary action andin effect the resulting brush element is a unitary structure.

Our present improved method of making brushes is not limited to use tothermoplastic material such as described above for the stranded brushmaterial, but may be utilized in the manufacture of dense brush-likestructures capable of being circularized or similarly formed'where thebrush material consists of fine wire strands.

The present invention further comprehends the method of mountingbrush-like structures produced as aforesaid, particularly when incircular or similar form so as to maintain the free ends of the strandedbrush material in close relationship one to the other as is desirablewhere the brush is to be utilized not merely as a brush in the ordinarysense but as a seal and/or loadbearing device. 7

To the accomplishment of the foregoing and related ends, said invention,then, consists of the steps and means hereinafter fully described andparticularly pointed out in the claims.

The annexed drawing and the following. description set forth in detailone method and one product exemplifying our invention, such disclosedprocedure and product constituting, how-y manufacture may :be carriedout, ;.such figure including a perspective view of a brush element asformed by such method;

Fig. 2 is a central longitudinal section through an apparatus adapted tobe used in carrying-out the present method, several accessory partsbeing shown in addition to those appearing -1;

Fig. 3 is a side elevation of-a brush elementas produced by the presentimproved -method;;-

Fig. 4 is a transverse section of such element taken on the planeindicated by; lined-=4, Fig. 3;

Fig. 5 is a side elevation of such element similar to that of Fig. 3 butshowing the element-with its base in flexed condition;

Fig.6 illustrates a plurality-0f elements-as as.- sembled. tov form .asorcalled brush. strip;

Fig.7 is a'transverse section, of such brush strip. as. indicatedbytheline. '|-'-1, Fig. 6

Fig.3 is a view similar to, Fig. 6 but showing-a different method. ofassembling suchbrush elements on. a supporting base or brush. back;

Fig; 9 .isa central longitudinal section, similar to that iFig.2,'through a modified form of apparatus, adapted tov be .used incarrying out the present method of. manufacturing brush-like structures;

Fig; 10 .isa .side elevation with parts broken away to show the interiorconstruction of a circular brush-like. structure made in accordance withour improved method, adapted for use as a brush. seal for a bearing;-

Fig. 1l:is a transversesectionon. the line I l.-l l, Fig 10.:.

Fig. 12 is a centralaxial view. of a typical bearingcshowingrthe. mannerin which .such brushlike. structure is applied thereto .asa seal; and.

Figs-=13 isa transverse sectional view of such bearing taken throughsaid seal .as. indicated by the line-.l.3--l-3, Fig. 12.

Referringmto. Figs. '1 and 2, theindividual strands or filaments-uutilized. to form the present improved; brush element will be drawnclosely compacted..parallel relation from theskeinsor reels in. which.filamental material. of .the. char.- acter previously described isregularly supplied by. .the ,manufacturer. Such; stranded: or filemental.materialnsually comes. in the form-of a multiple. strand, the numberof. individual strands 0 :1; fi aments. com rised therein varyinwith-the.

diameter,- i. e. fineness, of the individual strand.

The assemblebody- A "of strands dthus provided, is carried using such,supporting or guiding.

een iesmeybe necessary, to; a .pre sl onth der p i at;.. ustr ted, mF s..1- and 2-; .As-

1BQL QWnL s c press. co p ises: simp y tw die-.lmemh rs. thefirstofwhichis o' r. n tocab ysmov l w t n. a 5. 0. 514 in the-second: y/11 ov e; a 1. eul r;. e ning. hrou h wh ch e-a emb dbodim of s nd sles;w l b un ers and t at. t e; p rt c lar:

shape of such die opening 4 maybevaried dependipgti pqn theshdpe whichit is desired, the

finish biiush element should take. By :alter nately raising and-loweringdie member; 2 the. pressure onthe-strandedbodyA may be released;

to. permit Such body to be advancedany predetermined dis tance, desired.and then tightly cl m e rzw h at e i pe ina Assofliatfld yvith theforward face-of-the press.

thus composed of die members 2 and 3 is a shearing blade 5 and a heatedmember 6, each of which is mounted so as to be capable of movementacross and in close fitting contact with such face. Since member 6 isheated, as indicated, its range of movement will desirably be such thatit will normally lie clear of-zthe adjacent press member, as illustratedin Fig.2. Said member-6 may be conveniently heated by electricalresistance wires 1 suitably imbedded therein or in any other manner asmay befound desirable.

Since the ends of the component strands or filtmentsi-of body: A.:asinitially assembled will be difiicult of alignment, the operation isintiated byadvancing such=body A through di opening Q until allof-thecomponent strands or filaments project beyond-the forward face ofthe press. Thereupon die member 2 is moved downwardly so -as tightly tocompress the portion of such body A liying within opening 4 and theshear blade or-kniief5 ismoyed-tosever the projectin ends of the,component; strands.

Next...heat edmember, .6 is moved acrosszsuch; forward face;ofthediemembers and, the exposed.-

end of. the strandsia comprised in the portionof body A thus heldcompressed indie. openingx ki The temperature at;which;;memb er 6 :ismain. tained willpf course; very; with the particular. syntheticplastic;compound-whereof strands. I f rme utsucntemnerature will besunrciently high so that as a result of the movement of member; 6, asjust described, across the exposed end of the assembled, body Ofistrands: thelatter;

will be rendered sufiic-iently plastic .to interiuse and form a thinlayer ofthematenial tOqWhiCh each individual strand; composing; thebody: is in-i tegrally joined.. The effect is very much like a searingaction exceptgthat; the; composition. is .un--

changed; the ends; of, thev brush .materialbeing As shown-,in;Fig, 2,.theheating member 6 is of. u s a alzmass,:containing a number.- ofheating elements: 1,, whereby; it may be maintained at, a propertemperature sufiiciently high thus to interfuse, such endsof thestrandswithout dam:-v age thereto during rapid, travel .1 thereacross.

Thermoplastic,-materials are damaged. ifysube;

jected to-v too high temperatures; The. massoi such heatingmemberfiissufiicient to provide; a substantial heat -reservoir,with consequentinsigenificant lowering of the temperature of such. member during thefusing-operations The nextstep in theoperation. willbe to. raisepressmember 2 so; as-to relieve, the pressure on the body ofbrush-material; held in ,dieopening4.

Thereupon such body is advanced; so as to: prio jectbeyond. theiorwardface of. the'press-a dis,-,

tance equaLto that which it is desired the strands.

b which enter into the finished brush element B shouldhave. Thebody ofvbrush material is now again clampedjni-th press by. downward movementof; die memberdg following-whichrshearblade 5 is actuated-tocutoff.theprojectingQQrtion, of the body, thus. producing thebrushselement .3as illustrated 4 in; Fig. 1 wherein. the .com-

ponent-strandsb are individuallynnitaizily and firmly attachedto thebase-Z -whichis shown; as, a thin, sheet like base having appreciableithick- 6. 5

The sequence of operations just described may thereupon be repeatedindefinitely until the stranded body A derived from a particular source(group of skeins or reels) is exhausted. Since the action of the heatingmember 6 is practically instantaneous, the sequence of operations may berepeated quite rapidly to form and sever from the stranded body Asuccessive brush elements B.

As indicated, the interiusion of the ends of the component strands b ofsuch brush element can be very accurately controlled so as to provide abase b of uniform thickness or thinness. Where the brush element, andthus its base, is of rectangular form, as illustrated in Fig. 1 (seealso Figs. 3 and 4), the thickness of said base will desirably be suchas to render the same relatively rigid transversely of the element butflexible longitudinally of the latter. In other words, the element maybe readily given a curvilinear form in its longitudinal direction, asillustrated in Fig. 5. On the other hand, as illustrated in Figs. 6 and7, such element is equally adaptable for assembly in a channel base C ofthe type used in the manufacture of so-called brush strip which as atpresent made usually consists of a metal channel within which strandedbrush material doubled about a retaining wire is held by compressing theside walls of the channel inwardly. Due to its condition of relativeinflexibility transversely of the fusion produced base I) the presentimproved brush elements B may be directly seated in such channel C andupon similarly bending in the side walls 0 the element will be securelyattached to the channel base C, as best shown in Fig. 7. Accordingly, byclosely juxtaposing a series of elements B in such a channel base C, asshown in Fig. 6, a brush strip of indefinite length may be produced, andsince the elements B are flexible in a longitudinal line the resultingbrush strip may be similarly bent, if required, to fit a curvilinearsupport.

Brush elements B are of course likewise adapted for direct attachment byadhesion of their bases b to any desired supporting base or back,

as illustrated in Fig. 3, where a series of such elements is shownattached by means of a layer of cement d to a block D which may consistof wood, metal or any other suitable material. Inasmuch as the bases 17of the brush elements B constitute an integument for the correspondingends of the component strands of brush material in such element, thecement or other adhesive thus used to attach the elements to support Dwill not penetrate between the filaments or even come in contacttherewith. Accordingly, none of the hereinbefore mentioned difiicultyattending the use of a cement or like binder is involved.

It should be pointed out that if desired the brush elements whereassembled in a channel C to form a brush strip as illustrated in Figs. 6and 7 may similarly have their bases cemented to the strip as anadditional means of securing the elements to the latter.

While in Fig. 8 an aligned series of brush elements B is shown asattached by the cementitious layer d to the supporting base or back D,it will be obvious that such elements may be similarly attached inspaced relation both longitudinally and transversely of the back.Furthermore, by making the elements of appropriate form and size, e. g.in the form of round bundles instead of the rectangular shapeillustrated, the eifect of individual bristle tufts may be obtained byattaching elements of this type in spaced relation, as described, ontothe supporting base or back.

. The modified method of manufacture illustrated in Fig. 9 involves theuse of a press I comprising two die members 2 and 3, the same asillustrated in Figs. 1 and 2, and the body A of strandedv or filamentalmaterial will be advanced through such press in the same manner asbefore so that successive sections of the closely compresed material maybe cut off by shearing blade 5. However, instead of utilizing a heatedmember 6, which upon movement, across the exposed ends of such shearedbody held between press members 2 and 3 will render such endssufficiently plastic to interfuse and form a thin layer of the materialto which each individual strand composing the body is integrally joined,a member I!) is mounted for similar movement. "This member, asdiagrammatically illustrated in Fig. 9, comprises a chamber adapted tocontain a body of the plastic material in fiuid condition, and,extending from the lower end of such heated chamber, a nozzle llmountedso as to be capable of movement across and in close fittingcontact with the forward face of the press. ,The transverse extent ofthe opening in said nozzle will be slightly greater than that of theassembled body A of strands held in the press and thematerial in thenozzle will be maintained at the desired temperature by means ofelectrical resistance wires i2 imbedded in the nozzle, or other suitablemeans.

Movement of the nozzle is correlated with that of the shearing blade 5so that following the severing of the projecting section of strandedbody A the opening in the nozziewill be causedto pass across the exposedends of the body held in the press. The temperature of the material inthe nozzle will be sufficiently high so that as a result of the movementjust described the exposed ends of such assembly body will be renderedsufficiently plastic to interfuse and form a thin layer of the materialto which each individual strand composing the body is integrally joined,just as before. The base layer thus-produced will also include of coursesome of the heated fluid material supplied through the nozzle, but theresult will be the production of a brush element substantially asillustrated in Figs. 3, 4 and 5, when the body A of filamental brushmaterial is next advanced and the projecting portion thereof shearedoff, except that the base I) of such element may be made of somewhatgreater thickness due to intrusion of such molten plastic from suchnozzle.

As previously indicated, while our improved method of brush manufactureis particularly adapted for use in making brush elements as describedfrom filamental material composed of plastic fibers, such method is alsoadapted to the manufacture of the elements in question from fine metalfilaments or strands. Particularly where the element is to be made fromthe latter, the modified construction of apparatus illustrated in Fig. 9will be desirably employed. In such case the molten material suppliedfrom chamber ll through nozzle i2. to the cut-off ends of the body ofstranded material held in the press will be molten metal, preferably thesame as that of which the strands are composed or one having acomparable temperature of fusion so that the ends of the strands thusheld in the press will be interfused to provide. a thin base capable offlexure in its longitudinal direction.

A series of brush elements B thus produced is shown in Fig. 10 asarranged in a circular channel-form base C which differs from the base(3 7 of -the construction illustratedin-Figsns and '7 in that the sidewalls 0 thereof extend a sub-: 'stantial distance beyond the base b otthetbrush. element and are bent inwardly toward the median plane-camelatten- As a resulttheouteriace of the brushelement-or assembled-seriesof such elements may be laterally compacted to such degree-as may beround desirable ion-the use to. which the elements in i such asselnbledvtorrn. are to beput, or, conversely, as illustrated in Fig. 12,suchouter-face may be allowed to spread so that the outerwidth or themember is greater than that-ofthe-base. I

Onesuchuse, -viz.-as-a brush seal for a bearing, is illustrated in Figs12 and 13. As there shown; the-circular base C is-press fittedorotherwise closely held withinthe-journal J of thebearing adjaeentthebali race-R which terms the bearing proper for the-shaft Srotatably'supported in such journah The laterally compacted outer-faceof the-filamentous brush material heldinbase' C will closelyandyetyield-ingly contact with the cylindrical surface of i the shaft andprovide a most effective-forniofsealagainst the entrance of dust orevenobiectionable gases into thebearing proper erany mechanism lyingbeyond such bearing. When the-brush element is conformed and secured tothe innenp'eriphery of an annular support asthus shown in- Figs. 12 and13 with the strands extending generally radially inwardly there-learesultant-spreading-of the already compact material at the brush face,laterally con-lined and supported-- by ltheuradially inwardly flaringside members 0'. Onthe other hand, when the brush element-iscircularizedas shown in Fig, 10 1 or similarly deformed to conform to aconvex mounting. there-is-naturally a resultant lessening of the densityor -the brush face since such face lies at -theouter periphery;- Theside walls 0' of the-i-channel formhbase C may accordingly beinclined-toward one another as shown inhFig. 11 to compact suchbrushface, the latter-now being narrower than' any other portion of thestranded body.

We areaware thatithasheretofore been proposed, asin Patent No'. 885,032to De Ferranti; to usela filamentous element'on the order of a brush asa sealior packing inzeonjunctionwith a bear- However.,-so.far as we areaware no som mercial use has ever been made ofsucha sealbecauseof thefailure to provide a construction of bnushiadasptedto this particularkind oi service. This it is believed-is due to-failure to a preciate;the fact that forming a brush convexly', as

by'circularizing the. base thereof-about the err-- ternahsurface of acylinder,- causes the-free ends ofithe filamentstc separate and formur'idesi-rable spacing and passageways through: the seal In the presentconstruction, .in the first place, not only is the circularizingpt thebrush elements greatly facilitated byitheir unique construction, but theobjectionable feature just referred-td-is" eliminated by laterallycompressing the body of filamentous material in' 'such a manner that'the free ends remain in close proximitm one to--an-- other,--af-tervtheyhave been: formed to there quiredshape.

Furthermore, by introducing between the strands of filamentous materialofa membersuch as illustrated in Figs. 1-0;11v and i2; a resilient,

rubberelik'e material," such member maybeadapted for useas-aresilient-load-bearin'g'and abrasionresisting devices To -transfor nithe member to this: user-after being' forr-ned the; circular shapeillustrated,- it' i will be placed'-- in a iiiold along with-therequisite quantity ofi'ubbe'rlike material-in fluid orplastie-condition-andthen the latter- I will be cured in the usualmanner: I

From the foregoing it will be seen that the present improvedconstruction of brush'eleine'nt not only lends-itself to rapid andeconomical manu facture, but is ad aptedfor use in a variety of ways-inthe constr'iiction oibrushesof different types, Thus the brush strip; asillustrated-in Figs6 and 7, may beused to form-eithera flat; circular-orcylindrical brush by attaching the channel base C-to a suitable support.Furthermora-the component element B; where designed for use in themaking of suchbrush strip=,- may be made considerably longer thanillustrated Toy-assembling a correspondingly-larger body A or thestranded or filamentousmaterial and spreading the sameout fiatwise-tofill a-oorrespondii-i'gly- Wider diespace 4 iii-thepress composed-of diemembers-2 and-3'. It should be stated that the herein --describedshort-trimmed form of brush elementcompcsed (if-relatively finefilamentous material, in addition to the above described useinbearingseals; has been-found to serve with a high degree ofsatisfaction-as a seal around operiable windows L and-doors conveyancesand buildings; A brush suitable iorsuch use -is cur rently in demand forsealing purposes in aircraft gun turrets where the gunner must beprotected fremthe high velocity stream of very cold" airthat-wouldotherwise interfere with his efficiency. Rubber sealshavebeentound entirely unsuitable forthis-purp'ose and in this-and-other-fields a brush element-suchas described,-particularly wheremounted ina suitable channel base to form a brush strip, presents-markedadvantages Similarly' there may be other fields Of-use for thepresentimproved-brush element where its func tion is not precisely that of abrush-in-the ordinary'sense ofthet'erni.

While in the foregoing description thestranded or filamental brushmaterial is" composed-either of thermoplastic c'on'opound on tne oreerof those specifically identified, or of: wirestrands, it'is alsopossible to utilize thepresentinipreved method for fabricatingbru'shes-out oi other-inaterials such as natural fibers or metal-strandsby first applying to the latter a oo'atuig of suchthermoplastic:materiall i such coatingmay then lee-fused and theindividual strands unitedto the resulting: integumcntalbas'e in the sarire manner as where the strands are composed wholly of thermoplasticmaterial.

Itwill'be' understood'lthat: the term thermo-- plastic materiahas usedhereinis intended to apply equally totsynth'etic fiber formingproductssuch asdesc-ribed as Well asthevarious metals which-areaavailable inistranded form and. suitable for useiru brushes Other-modesof applying the p'rinoipleof our inyen-tionamay beemploye'd -instead ofthe one explained; change being .made'i as regards the product andmethod herein disclosed',= pziovid'ed theistep' or steps stated by anyof-the followihg claimsor the" equivalent of-sueh stated step or stepsbe employed.-

We thereforeparticularly point out and dis-- tinctly -clairnasourinvention:-

1. =In a method of making brush elements and the likeiro-nr strandscoziiposed atle'ast in part of thermoplastic material; thesteps whichcomprise retainin'g a body=oi s'uchshamans-- posed in substantiallyparallel relationship in de' e sired cross sectional shape'with alignedends-cit posed -afid then interfusin'g S1101! 'endSWith' add?- tion offurther molten material to form a thin, flexible sheet base for suchelement wherewith the individual strands are united.

2. The combination with a brush element comprising a closely compactedbody of thermoplastic stranded material, the component strands thereofbeing joined by fusion at their base ends to form a thin flexible sheet;of a concave support for said element to which such flexible sheet isconformed, and means laterally confining and supporting said strandedmaterial with the latter forming a brush face of greater width than thewidth of said body of thermoplastic stranded material where joined tosaid sheet.

3. As a new article of manufacture, a narrow elongated channelformsupport and an elongated flexible, deformable brush element clampedtherein by the sides of such chanel, said brush element comprising abody of stranded thermoplastic material joined by fusion at the baseends of such strands into a narrow sheet of sufficient transverseinflexibility relative to the compressibility of said body of strands tobe thus securely laterally clamped by such channel sides and ofsuificient longitudinal flexibility to readily conform tocircularization and like deformation of said channelform support.

4. In a method of making brush elements from strands composed at leastin part of a thermoplastic material, the steps which comprise laterallycompressing a body of such strands disposed in substantially parallelrelationship in a die, such strands being drawn from a continuous sourceof supply of indefinite length, passing a substantial body of moltenthermoplastic material across the assembled ends of such strands underpressure in contact therewith, thereby momentarily fusing the endportions thereof and also intruding such molten material to form a thin,quickly solidifying film of such thermoplastic material including suchfused ends, thereby forming a unitary thin flexible sheet base,releasing such pressure, advancing such body of strands a predetermineddistance beyond such die, again compressing such body of strands,severing such body between such die and such 10 integral unitary baseportion to produce a brush element, and thereafter repeating such cycle.

5. The combination with a brush element comprising a closely compactedbody of thermoplastic stranded material, the component strands thereofbeing joined by fusion at their base ends to a thin flexible sheet; ofan annular support for said element to the inner periphery of which suchflexible sheet is conformed and secured with such strands extendinggenerally radially inwardly therefrom, and radially inwardly flaringsupporting means laterally confining and supporting such strandedmaterial, the brush face of such element being of correspondinglygreater width than the base portion thereof.

6. In a method of moving brush elements from strands composed at leastin part of a thermoplastic material, the steps Which comprisecompressing a body of such strands disposed in substantially parallelrelationship in desired crosssectional shape in a corresponding dieopening, shearing off the portion of such body projecting beyond suchopening, and then interfusing short but appreciable lengths of the endportions of such strands held thus compressed in such die by heating thesame by intrusion of additional molten thermoplastic material to form athin, flexible, sheet base for such element wherewith the individualstrands are united.

RUBEN O. PETERSON. FLETCHER C. MILES.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 764,898 Mumford July 12, 1904 1,037,830 McMillan Sept. 3, 19121,118,156 Schoepe Nov. 24, 1914 2,100,138 Heldt Nov. 23, 1937 2,171,591Minich Sept. 5, 1939 2,303,800 Swann Dec. 1, 1942 2,310,186 Abrams Feb.2, 1943 2,329,222 Schlegel Sept. 14, 1943 2,341,823 Smith Feb. 15, 19442,438,156 Dodge Mar. 23, 1948

